In an internal combustion engine (hereinafter also referred to as a combustion engine or simply as an engine), heat energy released as the result of the combustion of fuel is converted into mechanical energy. The engine is provided with control means for controlling the energy conversion and an engine output shaft is caused to be rotated by the mechanical energy resulting from the energy conversion. It is possible to vary the torque derived from the rotation of the engine shaft by correspondingly varying the conditions under which the energy conversion takes place. Recently, there have attempts to effect optimum control of the energy converting conditions with the aid of an electronic computer. The control of the energy converting conditions, i.e. the conditions under which heat energy is converted into mechanical energy, is now one of the important controls for the operation of an internal combustion engine. In addition, it is important to carry out such control until energy conversion has been performed in a normal state in a combustion engine.
For starting the operation of a combustion engine, a starting (or starter) motor is first turned on to thereby rotate the engine shaft in order to cause energy conversion to take place. As is well known in the art, the conventional method of starting the engine operation involves the disengagement of the clutch and subsequently the engine is rotated by means of the starting motor, while the fuel supply to the engine as well as the ignition timing are controlled so as to be suited to the engine starting conditions.
However, when the driving of the engine shaft for starting the running of the engine is performed by resorting to only the starting motor, there may then arise the case where the engine operation can not be started due to possible failure of the starting motor or consumption of a power supply battery. Further, in the case in which the engine operation is abruptly stopped in the course of the running of a motor vehicle, it is conceivable to continue the running of the vehicle without stopping by re-starting the engine operation by making use of inertial energy of the vehicle. In other words, it is necessary to take into consideration the starting of the engine operation by applying to the engine shaft a rotating force available from the vehicle wheels in the control of the engine starting operation. In this connection, there has been yet no proposal as to the method of starting the engine operation by rotating the engine shaft by making use of torque or inertial energy available from the vehicle wheels in the hitherto known energy conversion control system which incorporates therein electronic circuits such as an electronic computer and the like.